Water testing finds E.coli in Duck Creek following manure spill, but impact 'could be worse'

Authorities are working to clean up 300,000 gallons of manure that spilled into Silver Creek on Monday after a holding tank valve failed at the Phil Robertson farm on County E in Oneida.(Photo: Sarah Kloepping/USA TODAY NETWORK-Wisconsin)Buy Photo

ONEIDA – Initial testing of bacteria levels in Duck Creek found E.coli contamination from a major manure spill is bad, but not at extreme levels, an expert said Friday.

An estimated 300,000 gallons of liquid manure spilled into Silver Creek, a Duck Creek tributary, on the Oneida reservation late Sunday or early Monday morning. It happened on the Phil Robertson farm on Brown County E when a valve malfunctioned, releasing liquid manure into a storage pit that already was nearly full. It overflowed and ran into Silver Creek.

The spill caused a fish kill in Silver Creek, but because of the flow of fresh water, the manure was quickly diluted, so that by the time it would have reached Duck Creek, it was no longer visible or creating a smell, experts said.

The state Department of Natural Resources has been collecting water samples from the area to measure the impact.

Testing for E.coli, a bacteria found in manure, showed levels that “weren’t atrocious,” according to Ben Uvaas, a DNR ag specialist. “I’m not saying they’re good, but they could be worse.”

Testing of Duck Creek water samples collected on the first day after the spill showed levels of about 600 colony forming units, Uvaas said. By way of comparison, when public beaches are tested in Wisconsin, advisories are posted when E.coli levels hit 235 of colony forming units, and, at 1,000 CFUs, beaches are supposed to be closed, Uvaas said.

A map of the flow of manure from a spill at Robertson Farm in Oneida(Photo: Ebert, Karl, )

Uvaas was unable to identify the baseline E.coli level for that part of the creek this time of year. He said E.coli levels in the creek likely are high anyway because of a number of upstream farms, so identifying the amount the spill contributed is difficult.

“Duck Creek is big, and all the activities upstream are adding to it, so you never know — it could have been 600 with or without it,” he said. “There’s never enough data collected. But the first results tend to be the most heavily influenced by the spill.

"I was surprised, pleasantly surprised” at the results, he said.

Levels likely will drop as the spill is further diluted and washed downstream, he said. By the time it reaches Green Bay, it’s impact will be immeasurable.

“I’m not going to say it’s harmless, because it doesn’t help anything, but we don’t anticipate acute water quality impacts as it moves farther downstream and more clean water moves in,” he had said earlier.

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Authorities are working to clean up 300,000 gallons of manure that spilled into Silver Creek on Monday after a holding tank valve failed at the Phil Robertson farm on County E in Oneida.(Photo: Sarah Kloepping/USA TODAY NETWORK-Wisconsin)

Cleanup at the spill site was continuing at week’s end, Uvaas said. Efforts to simply flush the solids into pits didn’t work as well as expected, so workers were using plows to scrape at the ground to move manure into the pits. The idea is to get as much solid manure as possible away from the creek before the next rain , he said. The National Weather Service in Ashwaubenon predicted dry weather though next Wednesday.

Brown County and Oneida health departments posted warnings at public access points on the two creeks to warn people against swimming or wading in the water or allowing their pets in the water, until further notice.

Uvaas couldn’t say whether Friday’s findings showed results that would lead to removing the warnings. The findings weren’t going to be formally passed on to the departments until early next week, he said.